The objectives of this proposal are to determine the roles of cobalamin (Cbl, vitamin B12) and transcobalamin II (TC II) in: 1) the production of immunoglobulins, and 2) bacterial killing. The needs of Cbl and TC II for release of IgG will be determined in both cultured, normal peripheral lymphocytes and in established lines of B lymphoblastoid cells. The interrelationship between the intracellular function of Cbl and IgG released will be determined if possible. Similar studies will be performed in the lymphocytes collected from persons deficient in Cbl or TC II. The functions of Cbl and TC II in bacterial killing will be studied in cultured, normal human granulocytes. Initial emphasis will be placed on studies of HMP shunt. These studies will also be extended into granulocytes collected from persons deficient in Cbl or TC II.